UNIT
10 – SELF-TEST
Part I: Matching
Match the letters in Column B with the numbers in Column A.
Mark the appropriate letters on the Scantron form for the corresponding
number.
Column
A
Column B
1. acidic solution
a. acid dissociation constant
2.
conjugate acid-base pair
b. [H3O+]
> [OH-]
3. amphoteric
c.
substance that changes color with changes in pH
4. alkaline solution
d. OH-
5. indicator
e. H3O+
6. hydroxide ion
ab. [OH-] = 1.0 x 10-7M
7. neutral solution
ac. [H3O+]
< [OH-]
8. hydronium ion
ad. a solution of NH4+
and NH3 in equal amounts
9. Ka
ae.
describes a substance that can act as both an acid and a base
10.
buffer
bc.
two substances that are related by the loss or gain fo a single hydrogen
ion.
Choose
the best answer and fill that letter in on the Scantron sheet by the appropriate
number.
Which
of these acids is monoprotic? (a)
CH3COOH (b) H2CO3
(c) H2SO4
(d) H3PO4
With
solutions of strong acids and strong bases, the adjective strong refers to: (a)
concentration. (b) molarity.
(c) ability to injure. (d)
degree of ionization.
A
12.0M solution of an acid that is able to ionize completely in solution
would be termed: (a)
concentrated and weak. (b)
strong and dilute. (c) dilute
and weak. (d) concentrated and
strong.
Which
of the following pairs consists of a weak acid and a strong base?
(a)
acetic acid, sodium hydroxide (b)
hydrochloric acid, sodium hydroxide
(c) sulfuric acid, ammonia (d)
acetic acid, ammonia
In
the reaction NH4+ + H2O ßà NH3 + H3O+, water is acting as a(n):
(a)
Arrhenius acid. (b) Bronsted-Lowry base. (c) Bronsted-Lowry acid.
(d) Arrhenius base.
Acetic
acid has a Ka of 1.8 x 10-5 and formic acid has a Ka
= 1.8 x 10-4.
(a) Acetic acid is a strong acid.
(b) Formic acid is a strong acid.
(c) Acetic acid ionizes more than formic acid.
(d) In equal volumes of 1.0 M acid solutions there are more H3O+
ions in the formic acid solution.
Which
of the following is/are properties of an acid.
(a) turns litmus paper red
(b) has a pH > 7. (c)
tastes bitter. (d) can contain
the hydroxide ion
A
solution in which the hydroxide-ion concentration is 1 x 10-5M
is: (a) acidic.
(b) basic. (c) neutral.
(d) none of these
The
products of the self-ionization of water are:
(a) H3O+ and OH-.
(b) HO- and OH+.
(c) OH+ and H-.
(d) H3O+ and H2O.
Which
of these solutions is most basic? (a)
[H3O+] = 1 x 10-11M (b) [OH-] = 1 x 10-4M
(c) [H3O+] = 1 x 10-2M
(d) [OH-] = 1 x 10-13M
A
0.0010 M concentration of a monoprotic strong acid would have a pH:
(a) greater than 3. (b) a pH equal to 3. (c)
a pH less than 3. (d) a pH
equal to 11.
Which
of the following would make a good buffer system: (a) HCl and NaCl.
(b) H3O+ and OH-
(c) HC2H3O2 and C2H3O2-
(d) HF and Br-
On
a titration curve the equivalence point occurs where: (a) there is a dramatic change in pH with slight addition of
reactant. (b) the moles of [H3O+]
= [base]. (c) a color change
occurs in the appropriate indicator. (d)
all of these are true. (e)
none of these are true.
When
a strong acid is added to titrate a weak base,
(a) the equivalence point is above pH of 7. (b) the equivalence point is below 7. (c) the equivalence point is right at 7.
(d) the pH starts out low and gradually rises as the acid is added.
PART II: Problems: Solve the following problems in the space provided.
Show work.
Write
the expression for Ka as directed for the
following substances in water. Assume
that only one hydrogen is ionized for the acids.
(Hint: Write the equation for the dissociation of the acid or base in
water first.)
a. H3PO4
b. NH4+
Complete
and balance the equations for the following acid-base reactions.
a.
H3PO4 +
Al(OH)3 à
b.
HI
+
Ca(OH)2 à
c.
H2SO4 +
NH3
à
d.
HCl
+ Al(OH)3
à
Use the Bronsted-Lowry definitions of acids and bases
to identify the acid, base, conjugate acid, and conjugate base in each of
the following reactions:
(a)
H2CO3(aq)
+ H2O(l)
ßà H3O+(aq)
+ HCO3-(aq)
(b)
HCl(aq)
+ H2O(l) à H3O+(aq)
+ Cl-(aq)
(c)
CH3COO-(aq)
+ H2O(l) ßà CH3COOH(aq)
+ OH-(aq)
Acid Base Conjugate Acid Conjugate Base
(a)
(b)
(c)
Calculate
the pH for the following solutions. State whether the each solution is acidic, basic or neutral.
(a)
[H3O+]
= 1.0 x 10-9M
(b)
[OH-]
= 2.64 x 10-10M
(c)
H2SO4
solution of 7.6 x 10-4M concentration
(d)
NaOH
solution with 4.5 x 10-2M concentration
What
range of pH values is associated with an aqueous solution of each of the
following salts? For each
answer write: > 7 , = 7 or < 7.
(a)
NaC2H3O2
(b)
Mg(NO3)2
(c)
(NH4)2SO4
(d)
K3PO4
(e)
For (d)
show with an equation why the PO43- ion produces the pH
level that it does.
Given
the pH of the following solutions calculate the ion concentration as
requested.
(a)
pH of
solution is 5.0; [H3O+] =
(b)
pH of
solution is 9.76; [OH-] =
(c)
pH of
solution is 0.73; [H3O+] =
(d)
pH of
solution is 13.0; [OH-] =
A
0.1000 M solution of acetic acid (CH3COOH) is only partially
ionized so that the [H3O+] = 2.25 x 10-3 M.
What is the Ka for this acid?
A
0.35 M solution of a newly synthesized acid, HX, has [H3O+]
of 4.1 x 10-2 M. What
is the value of Ka for this acid?
Give
the reactions for the addition of an acid and a base to the acetic
acid-acetate buffer
Classify
each of these statements as always true (AT), sometimes true (ST), or never
true (NT).
a.
Neutralization
reactions take place when salts are dissolved in water.
b.
An aqueous solution of NH4Cl is basic.
c.
The
buffer capacity is the amount of acid or base that may be added to a buffer
solution before a significant change in pH occurs.
d.
HCl-NaCl would be a good buffer system.
How many mL of 0.65 M HNO3 are needed to neutralize 50.0 mL of 0.90 M Ca(OH)2
